sending static files from Rails using litespeed

On my rails site, (served by Litespeed) I have a number of pdf files that should be accessible to members only. Currently I have them located in a subdirectory of the rails "public" directory. This, of course, does not restrict access to them.

Within rails, I could call the send_file method, and locate the pdf within my rails directory structure, thereby restricting access only to authorized users. But I have been told that rails should not be serving static files, because that is the responsibility of the web server.

I have read that in Apache, I could set a special HTTP request header with the path to the file I want the web server to send, like:
response.headers[`X-Sendfile'] = path